B5 Communicable Diseases Flashcards
what is a communicable disease?
a disease which can be spread from person to person
how are communicable diseases spread?
by pathogens such as bacteria or viruses
how do different diseases interact with each other?
one disease can put someone at risk of other diseases
one disease can also cause another
what are pathogens?
microorganisms which cause infectious disease
what are some examples of pathogens?
bacteria
viruses
protists
fungi
how do bacteria make humans ill?
once inside the body, they reproduce rapidly
they can then release harmful chemicals (toxins)
toxins damage tissues and make us feel ill
how do viruses make humans ill?
the virus invades the host cell
it then reproduces inside the cell
this is very damaging to the cell and cause it to burst open and die when the virus leaves
how do viruses reproduce?
they have to use a host cell
how are pathogens spread?
in the air (e.g. water droplets)
directly in water
direct contact by individuals
how can the spread of pathogens be reduced?
washing hands before eating
clean drinking water
isolation
vaccination
what type of pathogen is malaria?
a protist
what is the life cycle of the malaria pathogen?
an infected person is bitten by a mosquito. the pathogen passes into the mosquito.
the mosquito then bites a different person and infects them
what is a vector?
another organism which carries a pathogen from one person to another without being infected itself
what are the mains ways to stop the spread of malaria?
stop the vector from breeding - drain areas of still water, spray areas with insecticide
prevent mosquitoes biting humans - sleep under mosquito nets
give 2 examples of viral diseases:
measles
HIV
can antibiotics kill viruses?
no.
viruses cannot be killed by antibiotics
what are the symptoms of measles?
high fever
red skin rash
how is measles spread?
in droplets when an infected person coughs or sneezes
the virus then passes to a different person when the droplets are inhaled
what can happen if someone has measles?
complications can develop
this can cause damage to the breathing system and the brain
it can also be fatal
what are young children given to protect them against measles?
a vaccination
what are the symptoms of HIV?
a flu-like illness
what is the HIV virus doing to the cells in the body?
the virus is attacking the cells in the body’s immune system
this means the immune system becomes severely damaged
what happens when the immune system becomes badly damaged?
it cannot fight off other infections that people could normally deal with
it is also unable to fight cancer cells
what is the late stage of the HIV called?
the patient is described as having late-stage HIV or AIDS
this is fatal
what is the treatment for HIV?
antiretroviral drugs - stops the virus multiplying so it does not damage the immune system
these drugs are not a cure and they must be taken by the patient for the rest of their life
how is HIV transmitted?
through the exchange of fluids between humans
what are some examples of bacterial diseases?
salmonella food poisoning
gonorrhoea
what drugs kill bacteria?
antibiotics
how is the bacteria causing salmonella food poisoning spread?
by ingesting infected food
what causes the symptoms of salmonella?
the toxins released by the bacteria
what are the symptoms of salmonella food poisoning?
fever
abdominal cramps
vomiting
diarrhoea
what controls the spread of salmonella food poisoning in the UK?
all chicken are vaccinated against salmonella
how is gonorrhoea transmitted?
it is an STD
what are the symptoms of gonorrhoea?
thick yellow/green discharge
pain when urinating
how was gonorrhoea treated in the past?
it was treated with penicillin
however, antibiotic resistant strains of the bacteria are now common
what is used to treat gonorrhoea today?
different antibiotics (not penecillin)
what can stop the transmission of gonorrhoea?
use a condom - stops bacteria passing from person to person
get tested - they can then be treated and prevent it from being passed on
what are some examples of diseases in plants?
virus - tobacco mosaic virus
fungus - rose black spot
what are the symptoms of tobacco mosaic virus?
leaves discolour in a mosaic pattern
what does discolouration in leaves result in? (from TMV or rose black spot)
the rate of photosynthesis is reduced so the growth of the plant is reduced
what are the symptoms of rose black spot?
leaves develop purple or black spots
leaves then often turn yellow and fall off
how is rose black spot spread?
the fungus is spread by water or wind
what are the ways to treat rose black spot?
fungicides - kills the fungi
remove infected leaves and destroy them
what do aphids do to plants?
extract nutrients from the plant, stunting it’s growth
are insects a pathogen?
no
they do not cause an infectious disease
how can you spot diseases on plants?
growths spots discolouration stunted growth decay or rot malformed stems or leaves
how can you identify a plant disease?
use a garden manual or website
take the infected plant to a lab to identify the pathogen
testing kits containing monoclonal antibodies
what happens if there is a lack of the nitrate ion in plants?
it causes stunted growth
this is because nitrate is needed for protein synthesis and therefore growth
what happens if there is a lack of the magnesium ion in plants?
it causes chlorosis as magnesium is needed to make chlorophyll
the leaves lose their green colouration
what features does the physical defence system in plants have?
cellulose cell wall and waxy cuticle - difficult for microbes to penetrate
bark - a barrier to entry for microbes
what features make up the chemical response in plants?
antibacterial chemicals - kill bacteria
poisons - deters herbivores from grazing on the plant
what features make up the mechanical defence system in plants?
thorns - protect from being eaten by herbivores
hairs - irritate the mouth of herbivores making it difficult to eat
leaves that droop or curl when touched - might scare herbivores
mimicry - herbivores think the plant is something else so don’t eat it
